The present invention relates to a fuel pump driving apparatus which is used for example with an engine including a fuel injection system.
A conventional fuel pump driving apparatus of the above type is shown in Japanese Unexamined Publication No. 57-146044.
The apparatus of this publication is designed so that with a fuel pump driven by a motor having three brushes one of which is connected to a power source and the other two are grounded, a switching relay is connected between the grounded brushes and the ground such that either one of the grounded brushes is connected to the ground in accordance with the engine condition, thereby controlling the delivery rate of the pump.
By thus controlling the delivery rate in accordance with the engine condition, there is the effect of saving the power consumption of the motor and reducing the occurrence of noise.
With the apparatus of this construction, however, the effective utilization of the pump driven by the motor having the three brushes has not been satisfactory as yet and there has still been room for improvement.